Field of the Invention
The present invention relates to a paper feeding device and an image forming device including the paper feeding device.
Description of Related Art
An air-suction type paper feeding device has been known as a paper feeding device, which stocks paper of an image forming device in a stacked state and feeds the paper into an image forming unit.
As shown in FIG. 16, this air-suction type paper feeding device 200 includes flotation air blowing units 101, 102, a separation air blowing unit 103, a belt conveyance mechanism 105 (see FIG. 18), and a paper conveyance unit (for example, see U.S. Pat. No. 4,952,524). The flotation air blowing units 101, 102 blow air to the upper paper from both sides along the direction (hereinafter referred to as a width direction of the paper) perpendicular to the paper conveyance direction for the paper P (FIG. 16 shows index paper described below) stacked on a paper stacking unit, and float the paper P by sending air between pieces of the paper P. The separation air blowing unit 103 separates the uppermost paper P from the paper P floating with the uppermost paper P by blowing air from the downstream side in the paper conveyance direction of the uppermost paper. The belt conveyance mechanism. 105 is arranged above the stacked paper and feeds the paper P into the paper conveyance direction while sucking the paper P with a conveyance belt 104 (see FIG. 18) on which a suction hole is formed. The paper conveyance unit receives the paper P from the belt conveyance mechanism 105 and supplies the paper toward the further downstream side.
Then, when the paper is fed, the conveyance belt 104 stands by in a sucked state. The flotation air blowing units 101, 102 start blowing and float plural pieces of upper paper P. The separation air blowing unit 103 separates the uppermost paper P from the paper P other than the uppermost paper P. Then, the conveyance belt 104 is driven and only the uppermost paper P is fed into the conveying destination.
In the above-described conventional paper feeding device 200, the following problem has occurred when non-standard shape paper such as the index paper (or tab paper) is supplied.
In the index paper, a protruded index piece is formed on the edge of the paper, and positions of the index pieces in the longitudinal direction are different from each other so that the index pieces do not overlap. Thus, the index piece can be used as an index.
When the above-described index paper P is stocked, as shown in FIG. 16, the index piece P1 is set to face the upstream side in the conveyance direction so that the index piece P1 is not caught while being conveyed.
On the other hand, the width of a rear end regulating member 106, which aligns the end of the paper on the upstream side in the paper feeding direction, needs to be sufficiently narrower than the width of the index paper P so that the air flow from the separation air blowing unit 103, which is positioned on the downstream side in the paper feeding direction, is not disturbed. Therefore, when pieces of index paper P are stocked in a state where the positions of index pieces P1 are different, some of the index pieces P1 of the index paper P do not abut on the rear end regulating member 106.
In this state, when the plural pieces of upper index paper P are floated by air blowing from the flotation air blowing units 101, 102, and the separation of the uppermost index paper P is performed through air blowing from the separation air blowing unit 103, as shown in FIG. 17, sometimes the index paper P in which the index piece P1 does not abut on the rear end regulating member 106 is moved to the upstream side in the paper feeding direction by the separation air.
In this manner, some of the index paper P are shifted to the upstream side in the paper feeding direction. As shown in FIG. 18, when the index paper in which the shifting has occurred is supplied, the head portion of the index paper P right below the shifted index paper P is sucked by the conveyance belt 104. This causes double feed.
In order to solve this problem, it is considered to widen the width of the rear end regulating member 106 and form the rear end regulating member 106 in a comb-tooth shape, so that the separation air can pass through. However, there may be a problem that when the rear end regulating member 106 is formed in the comb-teeth shape with fine teeth, passing through of the separation air is blocked, and when formed in the comb-teeth shape with coarse teeth, the index piece P1 protrudes from a space between the teeth and the movement of the index paper P to the upstream side in the paper feeding direction cannot be prevented.
Although in the above example, a case where the positions of index pieces P1 of the index paper P are different in the width direction is exemplified, the following problem occurs also in a case where the index paper P in which the positions of index pieces P1 are the same is stacked.
That is, as shown in FIG. 19, when the position of the index piece P1 shifts relative to the rear end regulating member 106 and the index piece P1 does not abut on the rear end regulating member 106 with the sufficient width, as shown in FIG. 20, the index piece P1 of the index paper P, which has been separated by the separation air, is pushed to the upstream side in the paper feeding direction. Thus, sometimes the index piece P1 is damaged, or the index piece P1 is deformed and the index paper P is shifted to the upstream side in the paper feeding direction. As a result, similar to the example described above, it causes double feed.